共查询到19条相似文献,搜索用时 109 毫秒
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基于平面角谱扩展法和4×4矩阵传输理论,研究了拉盖尔-高斯光束(LGB)在含拓扑绝缘体(TI)周期性层状薄膜中的反射和透射特性,对线偏振的LGB入射到周期性层状薄膜中的反射场和透射场的强度分布进行了分析和详细讨论。研究结果表明,TI的拓扑磁电极化率(TMEP)和薄膜的周期个数对强度分布有很大影响,通过改变TMEP或周期个数可以操纵涡旋光的光场。所提方法不仅可以推广到其他含TI的多层介质体系,而且对进一步研究TI光子晶体中的光子能带结构和带隙具有一定的意义。 相似文献
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为了研究受限拉盖尔-高斯光束湍流传输时轴上光强分布,采用扩展惠更斯-菲涅耳原理方法进行了理论分析,得到了受发射圆孔限制的拉盖尔-高斯光束在大气湍流中传输时轴上光强的表达式.并运用MAPLE模拟,取得了不同湍流强度、波长和发射圆孔孔径下轴上光强的分布理论数据.结果表明,拉盖尔-高斯光束在不同阶数、湍流强度、波长和发射圆孔孔径下,真空和湍流较弱时,轴上光强在近场发生明显振荡,达到最大值后,强度明显开始降低,湍流较强时,传输很近距离强度就迅速衰减,并与其在真空中的传输特性进行了比较.这一结果对研究拉盖尔-高斯光束是有帮助的. 相似文献
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为了研究受限拉盖尔-高斯光束湍流传输时轴上光强分布,采用扩展惠更斯-菲涅耳原理方法进行了理论分析,得到了受发射圆孔限制的拉盖尔-高斯光束在大气湍流中传输时轴上光强的表达式。并运用MAPLE模拟,取得了不同湍流强度、波长和发射圆孔孔径下轴上光强的分布理论数据。结果表明,拉盖尔-高斯光束在不同阶数、湍流强度、波长和发射圆孔孔径下,真空和湍流较弱时,轴上光强在近场发生明显振荡,达到最大值后,强度明显开始降低,湍流较强时,传输很近距离强度就迅速衰减,并与其在真空中的传输特性进行了比较。这一结果对研究拉盖尔一高斯光束是有帮助的。 相似文献
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为了从系统的角度研究大气湍流对涡旋光束传播 质量的影响,根据广义惠更斯-菲涅尔积分和Kolmogorov湍流大气原理,利 用傅里叶光学分析方法和光束分步传播法对携带有轨道角动量(OAM)的 拉盖尔-高斯(LG)光束在湍流大气中的传播进行理论分析与数值仿真, 导出角谱形式的衍射模型及其对应的抽样限制条件。利用桶中功率(PIB,power in bucket)计算方法,分析湍流强度对不同OAM值的LG光束质量的 影响;引入高斯光束和点光源,对比评估典型光束的抗湍流能力。数值仿真结果表明:受大 气湍流影响,随着LG光束在湍流大气 中传播距离增加,光束会聚能力变弱有明显扩散;光束本身特有的环状光强分布及其相应的 相位分布都受到不同程度的破坏,损伤 程度与光束本身携带的OAM数有关;点光源对湍流的影响最为敏 感;高斯光束具有与小OAM值的LG光束相比拟的抗 湍流能力,且比大OAM数的LG光束有更强的抗湍流能力。 相似文献
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《Microwave Theory and Techniques》1972,20(10):662-669
Coupling coefficient, odd- and even-mode impedances, and the mode phase velocities are calculated for a pair of broadside-coupled strips embedded in a layered dielectric medium and enclosed by a rectangular shield. Large ratios of mode phase velocities can be achieved with this structure leading to novel performance characteristics for familiar coupled-line configurations such as the microwave C section. 相似文献
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Songsong Ma Chunyu Guo Chengcheng Xiao Fan Wu Michael Smidman Yunhao Lu Huiqiu Yuan Huizhen Wu 《Advanced functional materials》2018,28(37)
Topological materials boast exotic metallic surface states with linear dispersion and spin‐momentum locking, which makes them potential candidates for dissipationless electronic and spintronic devices. Here, it is theoretically predicted that intrinsic Te antisite defects (TePb) in the narrow‐gap semiconductor PbTe induce a band inversion, turning it into a topological crystalline insulator (TCI). To experimentally verify the exotic properties, TePb antisites are introduced into PbTe crystals via nonstoichiometric growth by molecular beam epitaxy. Semimetallic resistivity and distinct quantum oscillations are observed on the TePb doped PbTe. Most importantly, a π Berry phase is unambiguously revealed by a Landau index analysis, demonstrating the Dirac fermion nature of the topological surface states. The discovered TCI nature in TePb doped PbTe is further explored using magneto‐transport measurements under external pressure, and the theoretical calculations of band structures with applying pressure indicate a pressure‐induced Lifshitz transition. Besides, it is proposed that the contribution of bulk states to transport can be reduced by enlarging the inverted gap with strain. 相似文献
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根据菲涅耳衍射积分,研究了拉盖尔-高斯光束经过单缝衍射后的光强分布,发现拉盖尔-高斯光束经过单缝后衍射条纹会出现空心和发生弯曲,并与实验结果进行了比较.研究了拉盖尔-高斯光束经过单缝后的螺旋谱,发现单缝的存在会使螺旋谱展宽.给出了拉盖尔-高斯光束经过单缝衍射后的相位分布.研究结果可用于涡旋光束拓扑电荷数的测量. 相似文献
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S. G. Dmitriev 《Journal of Communications Technology and Electronics》2018,63(2):154-157
The potential of image forces for the charge in a three-layer medium (a dielectric film between two dielectrics) is considered in terms of electric fields (by definition) rather than potentials. It is demonstrated that the result differs from the usual result by a constant. Related issues are discussed. 相似文献
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本文考虑轴对称高斯型激光束在均匀介质及类透镜介质中的传播问题。本文采用作者以前所导出的正确方程,计及光束的衍射效应,求出了方程的解析解。在此基础上,讨论了激光束的宽度和波阵面问题。在均匀介质中,激光束将单调变粗;在类透镜介质中,激光束的宽度是z正弦函数,粗细交替出现。 相似文献
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Moment Method Analysis of an Archimedean Spiral Printed on a Layered Dielectric Sphere 总被引:1,自引:0,他引:1
A method of moments model is presented to analyze Archimedean spirals that are printed on a layered dielectric sphere. The model is derived assuming an arbitrary location of the spiral. Input impedance, current distribution and far-field results are presented and are shown to be in good agreements with other methods. 相似文献
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Field Enhancement for Dielectric Layer of High-Voltage Devices on Silicon on Insulator 总被引:6,自引:0,他引:6
Bo Zhang Zhaoji Li Shengdong Hu Xiaorong Luo 《Electron Devices, IEEE Transactions on》2009,56(10):2327-2334
Based on the continuity theorem of electric displacement including interface charges, the enhanced dielectric layer field (ENDIF) for silicon-on-insulator (SOI) high-voltage devices is proposed. The following three approaches for enhancing the dielectric layer electric field EI to increase the vertical breakdown voltage of a device VB,V are presented: 1) using a thin silicon layer with a high critical electric field ES,C ; 2) introducing a low-permittivity dielectric buried layer; and 3) implementing interface charges between the silicon and the dielectric layer. Considering the threshold energy of silicon epsivT, the formula of ES,C on silicon layer thickness tS is first obtained, which increases sharply with a decrease of tS, and reaches up to 141 V/mum at tS = 0.1 mum. Expressions for EI and VByV are given, which agree well with simulative and experimental results. Based on the ENDIF, the new device structures are given, and an EI value of 300 V/mum has been experimentally obtained for double-sided trench SOI. Moreover, several conventional SOI devices are explained well by ENDIF. 相似文献